FIELD OF THE INVENTION
The invention lies in the electronics field. Specifically, the invention pertains to a timer for an A/D converter having means for producing a request signal in order to produce a first request signal for the A/D converter to perform A/D conversion on an analog signal allocated to the timer during a defined time interval which is repeated cyclically.
In complex applications, various analog input signals have to be supplied to the A/D converter and converted at previously programmed times or in response to various events. The input signals to be converted can originate from different converter request sources which, in turn, are allocated a multiplicity of different signal channels. The request sources produce request signals for the A/D converter, in order in this way to request A/D conversion for a specific one of their signal channels from the A/D converter.
One of these request sources can be a programmable timer unit which, under clock control, produces request signals for the A/D converter. In particular, these timer units enable A/D conversions to be triggered cyclically. In this instance, the requests from the timer unit are synchronized with the other request sources using so-called interrupts, a so-called interrupt flag generally being set after every conversion. However, since the individual modules require a specific reaction time to respond to interrupt flags that have been set, exact synchronization of the different request sources is not always guaranteed.
Furthermore, when connecting a timer to an A/D converter which samples, i.e. equidistantly detects and converts, analog input signals, it is necessary to make sure that the A/D converter is not actively converting at an instant where the timer is requesting a new conversion. For some applications, such synchronization is very important.